When someone without invitation and against your will performs a full-on-tongues-n-all kiss on you but you are either too surprised/drunk/polite to push them away. The result of which is that you have effectively 'snogged' that person despite never having had any desire to do so.

Eurgh! I was just chatting to that freaky boy with the mono-brow last night when he mouth raped me. I was so shocked I didn't know what to do and before I knew it we'd already snogged.

This MUST be done when the mouth is open at its widest, to get the ultimate effect and the least chance of them biting your finger off. This must be a quick "in" "out" motion whilst the perp shouts "MOUTH RAPE". This leaves the victim feeling unsatisfied, violated and unable to finish their yawn.

I desperately tried to pull away, but she was too strong. I felt her tongue swishing around my mouth then she licked the roof of my tongue while I desperately tried to spit it out. When I was making my failing attempts, I felt saliva trickle down my throat. It was disgusting mouthrape.